Filter bag



June 19, 1956 w. D. CROPLEY FILTER BAG 3 Sheets-Sheet 1 Filed May 18, 1953 INVENTOH.

Will/a 0. Grop/ey ATTORNEY.

June 19, 1956 w. D. CROPLEY FILTER BAG 3 Sheets-Sheet 2 Filed May 18, 1953 IN VENT OH Will/a D. Crop/ey June 1956 w. D. CROPLEY 2,751,041

FILTER BAG Filed May 18, 1953 3 Sheets-Sheet 3 nvvzuron. William 0. Crop/ey ATTORNEY.

United States Patent FILTER BAG William D. Cropley, Canton, Ohio, assignor to The Hoover Company, North Canton, Ohio, a corporation of Ohio Application May 18, 1953, Serial No. 355,805

8 Claims. (Cl. 183-51) The present invention relates to suction cleaners and comes filled with dirt. The many attempts to achieve thisend have met with only partial success. There are many reasons for these failures not the least of which has been the lack of a simple design involving a minimum number of operations capable of being carried out speedily and accurately by automatic machinery with little or no handling by workmen.

Another difficulty confronting designers has been the provision of a satisfactory yet inexpensive inlet opening for attachment to the cleaner exhaust and including proper safeguards against the escape of dirt both during the use of the cleaner and upon removing the filter fromthe cleaner.

Yet a further problem has been the provision of a filter assembly employing a disposable filter of large dirt capacity in combination with adequate safeguards against the rupture of the filter wall due to the quantity and weight of the dirt collected therein.

The present filter bag design has been found highly successful in meeting these and numerous other requirements to a degree not heretofore approached and by a novel construction and arrangement of parts never before suggested. In essence this has been accomplishedin the present invention by passing a web of filter paper through a tubing andpleating machine of generally conventional design. The resulting pleated cylindrical tube is 'cut'into section of the desired length for individual filter bags. The top end is sealed closed while the inlet end is cut off on the bias. These pleats are then flattened against one another and stitched to the longer unpleated web of the tube to form a small diameter inlet opening to receive the suction cleaner adapter tube.

Further features of the design include a highly effective dirt valve formed from a rectangular sheet of paper secured across the lower side of the inlet opening.

Accordingly, a primary object of the present invention is the provision of a novel disposable paper filter for use on suction cleaners and the like.

A further object is the provision of a paper filter construction which can be manufactured at high speed by automatic machinery with a minimum of handling by hand labor.

Yet another object is the provision of a filter which is folded fiat and compactly as manufactured and which opens readily when installed on a cleaner into a cylindrical tube of large area and high dirt storing capacity.

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Still another object is the provision of a novel mode of pleating a filter bag to provide a large dirt collecting pocket to one side of the inlet opening and removed from the incoming dirty air stream when the bag is installed on a cleaner.

Another object is the provision of a new and simplified mode of forming the air inlet without the use of reinforcing materials and expedients considered essential to prior designs.

Yet another and important object is the formation of the pleats in echelon so that the flattened layers of paper at the inlet end are distributed about a portion of the periphery for reasons which become evident from the detailed description of the invention which follows.

Still aonther object is the provision of a new and improved filter assembly for use on a floor type suction cleaner.

A further object is the design of the filter inlet in such manner that the projecting and overlapping pleats provide a reinforced pilot for guiding the adapter into the filter inlet during its assembly to the cleaner.

Yet another object of the invention is the provision of a new and simple method of constructing a filter bag.

Numerous other objects and advantages of the invention will become apparent from the following detailed specificaiton taken in connection with the accompanying drawings in which:

Figure 1 is a side elevational view partly in section of a floor type suction cleaner using my unique filter bag;

Figure 2 is a perspective view of the filter bag in readiness for assembly on a suction cleaner and showing the inlet expanded to its full diameter;

Figure 3 is a sectional view through the body of the filter taken along line 33 on Figure 2;

Figure 4 is a sectional view along line 44 on Figure 6 and showing the position of the dirt valve member;

Figure 5 is a schematic view of the automatic tubing and pleating machine utilized in the manufacture of the filter; and

Figure 6 is a perspective view of the completed filter folded flat ready for packaging.

Referring first to Figure 1, it will be seen that the invention is shown as incorporated in a floor type suction cleaner having a main body generally designated 10. An electric driving motor enclosed within the body by a hood 11 has an axis extending generally horizontally lengthwise of the body. The forward end of its shaft opens'into a suction fan chamber having an exhaust air outlet 12 projecting laterally from the near side of the cleaner body as viewed in Figure 1. This fan has a centrally disposed inlet opening in its forward wall which is in communication with the usual suction air passageway leading into the downwardly facing suction nozzle 13. The cleaner body is supported on a pair of front carrier wheels 14 and a pair of rear wheels 15 in a well known manner. The suction nozzle is preferably provided with a rotary agitator driven by a belt coupled to a pulley at the forward end of the motor shaft. This pulleyand belt are accessible for servicing through a removable cover plate 16 at the forward end of the cleaner body.

The cleaner is propelled across the floor by a handle,

The filter assembly comprises a filter adapter tube 21 projecting rearwardly from the discharge end of a soft Since this mechanism forms no part of the present invention, it need not be described in detail.

rubber bellows 22. The lower end of bellows 22 merges with an elbow portion having an inlet passage 23 projecting transversely of the cleaner body and including any suitable means for detachably-coupling the same to the outer end of exhaust air passageway 12. The 'inlet end of elbow 23 is shown as nonrotatably mounted on the end of the exhaust but it will be understood that it may include a pivoting type coupling if desired. The bellows portion 22, however, is thin walled and very flexibleparticularly in a vertical plane. As a consequence, adapter tube 21 pivots readily and follows tie movement of the propelling handle as the same pivots about pins 19 in the use of the cleaner.

Adapter tube 21 is generally cylindrical and is provided with an annular depression 2 in which the resilient garter spring 25 is adapted to seat for the purpose of clamping the inlet end of the paper filter bag to the adapter. This spring rolls readily along tube 21 to a position at the base of the adapter in which position it is clear of the lowermost end of the filter bag. After the filter bag has been positioned on the adapter, the spring can be rolled up over the end of the filter and into depression 24 where it remains so long as the cleaner is in use and wherein it effectively seals the filter inlet to the adapter tube. It should also be noted that the upper end of adapter 21 is rolled inwardly at 26 to facilitate the assembly of the filter inlet thereover. The lower end of tube 21 may be flared outwardly at 27 so as to interlock with an interior channel in the upper end of bellows 22. Tube 21 may also be provided with a plurality of openings through which studs 28 on the bellows project for the purpose of locking the tube assembled to the bellows.

The filter assembly also includes an outer appearance bag 29 of porous fabric, or the like. Bag 29 conceals the adapter and the filter bag proper and also acts as a protective covering for the paper filter bag. The lower end of the appearance bag surrounds the rubber bellows 22 and may be secured to the inlet elbow 23 of the adapter assembly. The appearance bag is provided with a suitable closure such as a hookless fastener extending lengthwise of the bag and through which access is provided to the adapter assembly and to the filter bag. The upper end of the appearance bag is preferably closed and supported from the upper end of the propelling handle by the usual tension spring 29a.

It will be observed that the appearance envelope is so tailored as to enclose a rather large space on the underside of the adapter. Or, stated diflerently, the adapter is arranged to lie along the upper side of envelope 29 since it is designed for use with my novel paper filter having a large dirt storing pocket extending along its lower side and below the under side of the adapter.

The disposable filter itself and the general type of equipment used in its manufacture is illustrated in Figures 2 to 6, inclusive. One of the finished filter bags 30 is best illustrated in Figure 2. It comprises a cylindrical tubular body formed by a lower relatively narrow connecting web 31, an upper, somewhat wider connecting web 32 and two sets of pleats 33 extending along its opposite sides the full length of the filter. The arrangement of the unpleated webs and the interconnecting pleats is best shown in Figure 3. Note that the interior crease lines 34 of each set of pleats as well as the exterior crease lines 35 are spaced at progressively greater distances from a vertical plane extending along the longitudinal axis of the filter. Thus, creases 34 are closest to this plane adjacent connecting web 31 and at the greatest distance from this plane adjacent web 32. The same is equally true of exterior crease lines 35. Accordingly, the pleats may be aptly described as arranged in echelon.

As clearly appears from Figures 2 and 6, the pleats are folded flat against one another at the opposite ends of the filter. There are several obvious advantages in arranging the pleats in echelon. For example, the folds of paper at creases 34 and 35 unavoidably bulks larger than two thicknesses of the filter paper itself. Furthermore, and of particular importance, the echelon arrangement of the pleats provides a gradual change from the single thickness of the paper in webs 31 and 32 to the maximum thickness of a flattened set of the pleats. This will be best understood by reference to Figures 2 and 4. Referring to Figure 4, note that the thickness of the filter inlet increases gradually from the scam in the center of web 31 as one advances circumferentially in either direction from this point along the interior rim of the inlet. The same is true of the exterior rim of the inlet if one advances from the center of web 32 to the lateral edges of web 31. Of course, it will be appreciated that the thickness of the paper, as shown in Figure 4, is greatly exaggerated. In an actual filter made in accordance with the invention, the gradual change in the thickness of the inlet rim as one passes over the inner or outer edges of the staggered pleats is gradual and barely perceptible.

Among the other advantages of the echelon arrangement of the pleats is that the gradual change in thickness of the pleated inlet greatly reduces the tendency of the inlet to tear at the junction of web 32 with the pleated lower half of the inlet. It is also a simple matter to provide an effective and air tight seal between the filter inlet and the adapter tubeparticularly, in the area between the juxtaposed edges of creases 34, 34.

Let us now refer to Figure 5 for an understanding of the method of manufacturing the filter. A large roll of air pervious filter paper 36 is suitably supported on a shaft 37 at one end of a well known type of tubing and pleating machine generally designated 38. It will, of course, be appreciated that these machines are commercially available in a variety of forms and operate to crease and pleat the sheet of paper stock as it is advanced through the machine. The paper web 39 from roll 36 is fed through suitable guide and tensioning rolls 40 and into the pleating machine 38. It has been found that a roll of paper stock 31 inches wide provides a pleated filter bag of a desirable circumference for use on floor type suction cleaners and having the desired dirt storage capacity and filtering area. As web 39 is fed into the pleating machine, a strip of glue 41 may be applied to one edge of the web by a fountain feed device 42.

As the web reaches the exit end of the pleating machine, the opposite edges of the web have been overlapped and jointed together by the glue strip 41 to form a cylindrical tube and pleats 33 have been formed in echelon in the opposite side edges of the tube in the shape, size and form clearly shown in Figure 3. Just prior to the discharge of the tube from the pleating machine, its rear end is severed by suitable cutting knives and the forward end of web 39 is again severed on the bias to form the pilot inlet end of the next filter bag. Theshape of the inlet end is best illustrated in Figures 1 and 2. From these figures it will be clear that the inlet edge of web 32 is severed in a straight line 43. The remaining periphery of the inlet, including pleats 33 and the inlet edge of web 31, is severed along a curved line to form the rounded edge 44.

Only two additional operations are required to complete the manufacture of the filter. One of these steps is to fold over the upper end of the tube and to glue it closed against one of the flat side walls of the filter, as indicated at 45. A simple gluing operation has been found entirely satisfactory for this purpose, but if desired, the top end of the bag may be closed by stitching the folded end. The final operation is to pass the flattened pleats and lower web 31 through a stitching operation to secure these pleats to Web 31. The straight edge 43 at the lower end of web 32 is used as the guide for the stitching 46 which extends from one side of the bag to the other across the lower-half of the inlet.

In practice, it has been. found helpful to provide the bag with a dirt valve to prevent the escape of dirt through the inlet during the removal of the filter from th'e'adapter.

This valve has other functions including that of constraining the flow of incoming dirty air to the upper portion of the bag and preventing it from stirring up dirt already collected in the lower end of the filter bag.

The dirt valve is formed very simply by inserting a rectangular piece of paper 47 into the flattened inlet end of the filter bag. Preferably the width of the valve member is slightly less than the flattened inlet end of the tube so that it can be easily telescoped into the inlet. The lower end of this valve is held depressed against the pleats and web 31 and is secured thereto by stitching 46 or, if preferred, by strips of glue applied along its side edges as well as across its lower edge on the side facing the pleats. The lower end of the valve may be rounded to conform in shape with the rounded end 44 of the pilot portion of the inlet or square cut as illustrated in Figure 6. The free upper end of the valve extends upwardly into the body of the filter bag to a point appreciably above the end of the adapter tube 21. From the foregoing it will be apparent that the lower end of the valve provides a cover for the lowermost end of the pleats as well as a smooth slide surface which facilitates the insertion of the filter bag over the end of the adapted tube 21 during its assembly to the cleaner.

The assembly of the filter bag onto the cleaner is accomplished very readily and expeditiously. T he'operator first opens the hookless closure extending along the side of appearance bag 29. Using her left hand, the operator then grasps the flattened filter inlet across the top side of Web 32 and squeezes the opposite edges toward one another to expand the inlet to the shape shown in Figure 2. The projecting ends of the pleats and web 31 then provide a pilot for guiding the inlet over the upper end of adapter tube 21 as it is held in alignment with the inlet by the right hand. During this operation the garter spring 25 is located at the base of the adapter tube. After the filter has been telescoped to the position shown in Figure 1 on the adapter with the pleats lying along the under side of the adapter, spring 25 is rolled upwardly until it seats in groove 24 to clamp the inlet to the adapter in an air tight manner. The hookless fastener is then closed and the cleaner is in readiness for operation.

As the motor-fan unit discharges air into the filter bag, the air gradually opens the bag until the pleats throughout the body of the bag are fully expanded. The adapter tube will, of course, lie against the inner wall of the top web 32 while the lower half of the bag will expand downwardly as clearly indicated in Figure 2 to provide a large dirt collecting pocket underlying the adapter tube and dirt trap 47. The supporting spring connecting the upper end of the filter assembly to the propelling handle will cause the entire assembly to pivot with the handle as the cleaner is propelled over the floor. All the flexing in the filter assembly will be confined to flexible bellows 22 to the lower end of the appearance bag with the result that there is no flexing in the filter bag itself.

The cleaner may be used until at least the lower half of the filter bag is filled with dirt. If a much larger quantity of dirt is collected the filtering efliciency of the filter bag will decrease considerably and it is desirable to replace the filter with a fresh one. This is accomplished by opening the appearance bag, rolling the garter spring downwardly to the base of the adapter and then withdrawing the filter bag. In this operation, dirt trap 47 will prevent any dirt from escaping through the inlet and the latter may be closed by flattening web 32 against the lower half of the inlet as the bag is carried to a place of disposal. A new filter is then installed in the manner described above and the cleaner is ready for continued operation.

While it is preferable to construct the filter bag with the dirt valve 47, it will be readily apparent that this valve may be omitted if desired.

While I have shown and described but one embodiment of my invention, it is to be understood that this embodiment is to be taken as illustrative only and not in a limiting sense. I do not wish to be limited to the particular structure shown and described but to include all equivalent variations except as limited by the scope of the claims.

I claim:

1. A non-reusable paper filter bag for use on a suction cleaner comprising, a main tubular body formed from air pervious paper material with a pair of opposite substantially flat walls, said body having a plurality of pleats extending along diametrically opposed sides of said body for the full length thereof intermediate said walls, said pleats forming inner and outer staggered creases throughout their lengths, means permanently closing the upper end of said body with the upper ends of said pleats flattened against one another, the lower end of said body having an air inlet opening of such size as to mate with and closely engage in air tight sealing relationship a filter adapter of the suction cleaner, one side of said inlet being formed by one of said flat walls and the remainder being formed by the remaining peripheral lower edge portion of said body including flattened lower ends of said pleats arranged in staggered relation so that the inner creases are offset with respect to each other at said inlet.

2. A non-reusable paper filter bag as defined in claim 1 including means for securing the lower ends of said pleats flattened against the other flat wall of said body.

3. A paper filter bag for use on a suction cleaner comprising, a single rectangular sheet of air pervious paper, the opposite longer edges of said sheet being joined together to form a tube, the walls of said tube being folded to form two sets of pleats extending lengthwise thereof on the opposite sides of the tube, said pleats forming inner and outer staggered creases, said sets of pleats being interconnected by a pair of unpleated webs adapted to lie in closely spaced parallel planes when said pleats are collapsed together, means closing one end of said tube with said pleats collapsed, said filter bag having an inlet opening at its opposite end, said inlet opening being formed in part by one of said unpleated webs and in part by a portion of the end of the other of said unpleated webs and by adjacent flattened ends of said pleats arranged in staggered relation so that the inner creases are offset with respect to each other, said inlet being of such size as to mate with and closely engage in air tight sealing relationship a filter adapter of the cleaner.

4. A paper filter bag as defined in claim 3 including a panel of thin flexible material located in said inlet opening and cooperating with the inner walls of said filter to form a dirt trap, said panel being shaped so as to be readily received with said inlet opening with its inner end extending toward the closed end of said filter, and means securing the lower end of said panel to the rim of said inlet opening on the side thereof formed by said flattened pleats and one of said webs.

5. A paper filter bag as defined in claim 3 in which the inlet end of said filter is cut on the bias and so that the side thereof formed by said flattened pleats and together with one of said webs projects further than the other side of said inlet to provide a relatively stiff pilot for guiding a filter adapter tube into said inlet opening.

6. A paper filter bag comprising, an elongated tube formed of air pervious paper, said tube having a plurality of pleats extending along its opposite lateral sides interconnected by upper and lower unpleated webs, the upper web being wider than said lower web, the pleats at one end of said tube being arranged in staggered relation so that the creases of said pleats are offset with respect to one another, and means extending cross-wise of the end of said filter for securing said staggered pleats against displacement and for holding the same flattened against the end of said narrow web whereby the same cooperate with the adjacent end portion of said wider web to provide a tubular inlet for said filter, said inlet being of such size as to mate with and closely engage in air tight sealing relationship a filter adapter of the cleaner.

mean

7. A paper filter bag for use on a suction cleaner comprising, a single piece of air pervious paper forming an elongated tube having an inlet at one end, a set of pleats extending along the opposite sides of said tube interconnected by upper and lower unpleated webs, the creases forming the pleats in each of said sets being offset from one another in echelon formation whereby said creases are offset from one another when said pleats are flattened against one another, the upper of said webs being shorter than the other and shorter than said pleats at the inlet end of said tube, the pleats of each set being flattened against one another and against an end of said lower, longer web, and means securing said flattened pleats t0 the end of said lower web so as to form the lower side of a tubular inlet for said filter, said inlet being of such size as to mate with and closely engage in air tight sealing relationship a filter adapter of the cleaner.

8. A disposable paper filter for use on a suction cleaner and formed from a single piece of air pervious paper, said filter comprising an elongated paper tube having an inlet at one end, said tube having two sets of pleats extending lengthwise thereof at its opposite lateral sides, all portions of said pleats being spaced from the opposite sides of a vertical plane extending through the longitudinal axis of said tube, the pleats in each set being arranged in echelon O c: formation so that the creases thereof are offset from one another when the same are flattened against one another, upper and lower unpleated webs of paper interconnecting said sets of pleats, the upper of said Webs being shorter than said lower web and shorter than said pleats, and means for securing the ends of each of said pleats to the end of said lower web whereby the same cooperates with the adjacent end ofsaid upper web to provide a tubular inlet at one end of said filter bag, said inlet being of such size as to mate with and closely engage in air tight sealing relationship a filter adapter of the cleaner.

References Cited in the file of this patent UNITED STATES PATENTS 2,295,981 White Sept. 15, 1942 2,418,371 Sinellie Apr. 1, 1947 2,444,762 Waters July 6, 1948 2,637,409 Turner et a1. May 5, 1953 2,641,333 Woessner June 9, 1953 2,672,213 Cropley Mar. 16, 1954 FOREIGN PATENTS 55,656 Denmark of 1939 626,763 Germany of 1936 

